for the last 20 years, a mystery fever has baffled physicians in western Uttar Pradesh. Several theories have tried to identify the fever, but there has been more confusion than clarity (see box: Unidentified assassin), all the time taking a rich toll: an average of 400 children die each year due to the fever, with physicians and medical researchers failing to provide any reason for the deaths. In the absence of another name, it has come to be called the Saharanpur fever, after one of the worst hit districts.

Clueless about the identity of the disease, authorities have vaccinated children in the area against Japanese encephalitis (je) as a precaution. je is one of the possible causes of the mysterious fever but not many in western up tested positive last year.

While the region is waiting for the next attack, a group of doctors have come up with another explanation for the mystery disease: toxic pods of the weed Cassia occidentalis, which children